Polysilane compositions, methods for their synthesis and films formed therefrom

ABSTRACT

Polysilanes, inks containing the same, and methods for their preparation are disclosed. The polysilane generally has the formula H—[(AHR) n (c-A m H pm−2 ) q ]—H, where each instance of A is independently Si or Ge; R is H, —A a H a+1 R a , halogen, aryl or substituted aryl; (n+a)≧10 if q=0, q≧3 if n=0, and (n+q)≧6 if both n and q≠0; p is 1 or 2; and m is from 3 to 12. In one aspect, the method generally includes the steps of combining a silane compound of the formula AH a R 1   4−a , the formula A k H g R 1′   h  and/or the formula c-A m H pm R 1   rm  with a catalyst of the formula R 4   x R 5   y MX z  (or an immobilized derivative thereof) to form a poly(aryl)silane; then washing the poly(aryl)silane with an aqueous washing composition and contacting the poly(aryl)silane with an adsorbent to remove the metal M. In another aspect, the method includes the steps of halogenating a polyarylsilane to form a halopolysilane; and reducing the halopolysilane with a metal hydride to form the polysilane. The synthesis of semiconductor inks via dehydrocoupling of silanes and/or germanes allows for tuning of the ink properties (e.g., viscosity, boiling point, and surface tension) and for deposition of silicon films or islands by spincoating, inkjetting, dropcasting, etc., with or without the use of UV irradiation.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/617,562, filed Oct. 8, 2004, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of polysilanes andmethods of making the same. More specifically, embodiments of thepresent invention pertain to polysilane compounds, compositions andmethods for making and using the same.

SUMMARY OF THE INVENTION

Embodiments of the present invention relate to polysilanes, polysilaneink compositions, methods for making the same and methods of making asemiconducting film using the same. The compounds generally comprise apolysilane of the formula H—[(AHR)_(n)-(c-A_(m)H_(pm−2)R′_(rm))_(q)]—H,where each instance of A is independently Si or Ge; each instance of Rand R′ is independently H, —A_(b)H_(b+1)R² _(b) (where R² is H, aryl orsubstituted aryl), halogen, aryl or substituted aryl, but if q=0 and Ais Si, R is not phenyl; (n+b)≧10 if q=0, q≧3 if n=0, and (n+q)≧6 if bothn and q≠0; p is 1 or 2; (p+r)=2; and each instance of m is independentlyfrom 3 to 12. In general, n, b and/or q*m may be the number of siliconand/or germanium atoms in the polysilane according to the number averagemolecular weight (Mn) of the polysilane. The compositions generallycomprise the polysilane compound (particularly the polysilanes in whichR=H or —A_(a)H_(2a+1)) and a solvent in which the polysilane is soluble.

One method of making a polysilane generally comprises the steps of (a)combining a silane compound of the formula AH_(a)R¹ _(4−a), the formulaA_(k)H_(g)R^(1′) _(h) and/or the formula c-A_(m)H_(pm)R^(1′) _(rm) witha catalyst of the formula R⁴ _(x)R⁵ _(y)MX_(z) (or an immobilizedderivative thereof or which may be synthesized in situ from thecorresponding precursors) to form a poly(aryl)silane of the formulaH—[(AHR¹)_(n)-(c-A_(m)H_((pm−2))R^(1′) _(rm))_(q)]—H, where eachinstance of A is independently Si or Ge, a=2 or 3, and each instance ofR′ is independently aryl, substituted aryl, or —A_(b)H_(b+1)R² _(b)(where R² is aryl or substituted aryl); (n+b)≧10 if q=0, q≧3 if n=0, and(n+q)≧6 if both n and q≠0; k is an integer from 2 to 12, g≧2 and(g+h)=2k+2; p is 1 or 2, m is an integer from 3 to 12, p is 1 or 2, andr is 0 or 1; R^(1′) is the same as R¹, except that when R¹ is—A_(b)H_(b+1)R² _(b) or the silane compound of the formula AH_(a)R¹_(4−a) is substantially absent, R^(1′) may be H; M is a metal selectedfrom the group consisting of Ti, Zr and Hf, x=1 or 2, y=1, 2 or 3, z=0,1 or 2, 3≦(x+y+z)≦8, each of the x instances of R⁴ is independently asubstituted or non-substituted cyclopentadienyl, indenyl, fluorenyl,siloxyl, germoxyl, hydrocarbyl, hydrocarbyloxy, hydrocarbylamino, orhydrocarbylsulfido ligand; each of the y instances of R⁵ isindependently a substituted or non-substituted hydrocarbyl,hydrocarbyloxy, hydrocarbylamino, hydrocarbylsulfido, silyl, germyl,hydride, phosphine, amine, sulfide, carbon monoxide, nitryl, orisonitryl ligand, and X is a halogen; (b) washing the poly(aryl)silanewith a washing composition comprising water; and (c) contacting thepoly(aryl)silane with an adsorbent sufficient to remove the metal fromthe poly(aryl)silane. Alternatively, the method may first form apolyarylsilane in catalytic dehydrocoupling step (a), then include thesteps of (b′) reacting the polyarylsilane with (i) a halogen source and(optionally) a Lewis acid, or (ii) trifluoromethanesulfonic acid (HOTf),to form a halopolysilane; and (c′) reducing the halopolysilane with ametal hydride to form the polysilane of the formulaH—[(AH₂)_(n)(c-A_(m)H_(pm−2))_(q)]—H. This latter embodiment may alsoproduce a polysilane of the formulaH—[(AH₂)_(n′−s)(AH[A_(a)H_(2a+1)])_(s)(c-A_(m)H_(pm−2))_(q′)]—H, whereA, a, m, and p are as described above; n′ is independently an integer inthe same range as n above; q′ is independently an integer in the samerange as q above; and s is an integer less than n′ (generally from 1 to3; e.g., 1).

The present invention is directed towards the synthesis of semiconductorinks via dehydrocoupling of (aryl)silanes and/or -germanes. Suchsynthesis allows for tuning of the ink properties (e.g., viscosity,boiling point, and surface tension) and for deposition of silicon filmsor islands by spincoating, inkjetting, dropcasting, etc., with orwithout the use of UV irradiation. Thus, the invention further relatesto a method of making or forming a semiconductor film from the presentink composition, comprising the steps of: (A) spin-coating or printingthe composition onto a substrate (optionally, with simultaneous orimmediately subsequent UV irradiation); (B) heating the compositionsufficiently to form an amorphous, hydrogenated semiconductor; and (C)annealing and/or irradiating the amorphous, hydrogenated semiconductorsufficiently to at least partially crystallize and/or reduce a hydrogencontent of the amorphous, hydrogenated semiconductor and form thesemiconductor film.

These and other advantages of the present invention will become readilyapparent from the detailed description of preferred embodiments below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a first approach for the synthesis ofpolysilanes from arylsilane monomers by catalytic dehydrocoupling,halogenation, and reduction.

FIG. 2 is a diagram showing a second approach for the synthesis ofpolysilagermanes from arylsilane and arylgermane monomers by catalyticdehydrocoupling, halogenation, and reduction.

FIG. 3 is a diagram showing an approach for the synthesis ofpolycyclosilanes from cyclosilane monomers by catalytic dehydrocouplingalone.

FIG. 4 is a diagram showing an approach for the synthesis ofpoly(cyclo)silanes from arylsilane and cyclosilane monomers by catalyticdehydrocoupling, halogenation, and reduction.

FIG. 5 shows a GPC trace of a typical polyphenylsilane synthesized by anexample of the present method.

FIGS. 6(A)-(C) show ¹H NMR spectra of an isolated polyphenylsilane (FIG.6 a), polychlorosilane (FIG. 6 b), and polysilane (FIG. 6 c),synthesized by examples of the present method.

FIG. 7 is a graph showing the viscosity of exemplary polysilane inks asa function of the polysilane mass loading in the ink.

FIG. 8 is a typical SIMS profile of certain impurity atoms in anexemplary silicon film made by an example of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with thepreferred embodiments, it will be understood that they are not intendedto limit the invention to these embodiments. On the contrary, theinvention is intended to cover alternatives, modifications andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims. Furthermore, in thefollowing detailed description of the present invention, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. However, it will be readilyapparent to one skilled in the art that the present invention may bepracticed without these specific details. In other instances, well-knownmethods, procedures, components, and circuits have not been described indetail so as not to unnecessarily obscure aspects of the presentinvention.

For the sake of convenience and simplicity, the terms “C_(a)-C_(b)alkyl,” “C_(a)-C_(b) alkoxy,” etc., shall refer to both branched andunbranched moieties, to the extent the range from a to b covers 3 ormore carbon atoms. Unless otherwise indicated, the terms “arene,”“aryl,” and “ar-” refer to both mono- and polycyclic aromatic speciesthat may be unsubstituted or substituted with one or more conventionalsubstituents, to the extent possible and/or applicable. The prefixes“(per)alkyl” and “(per)hydro” refer to a group having from one to all ofits bonding sites substituted with alkyl groups or hydrogen atoms,respectively (e.g., “(per)alkylsilyl” refers to a silyl group of n atomshaving from 1 to 2n+1 alkyl groups bound thereto). The terms “silane,”“polysilane” and “(cyclo)silane” may be used interchangeably herein, andunless expressly indicated otherwise, these terms individually refer toa compound or mixture of compounds that consists essentially of (1)silicon and/or germanium and (2) hydrogen. The terms “arylsilane,”“polyarylsilane” and “aryl(cyclo)silane” may be used interchangeablyherein, and unless expressly indicated otherwise, these terms refer to acompound or mixture of compounds that contains or consists essentiallyof units having a silicon and/or germanium atom, a hydrogen atom boundthereto, and an aryl group bound thereto, where the aryl group may besubstituted by a conventional hydrocarbon, silane or germanesubstituent. The term “(aryl)silane” refers to a silane, polysilane orcyclosilane that may or may not contain an aryl or substituted arylgroup bound thereto. The prefix “(cyclo)-” generally refers to acompound or mixture of compounds that may contain a cyclic ring, and theprefix “cyclo-” or “c-” generally refers to a compound or mixture ofcompounds that contain one or more cyclic rings. For the sake ofbriefness, the terms “halo-,” “halide” and grammatical derivationsthereof may describe halogens as defined in the Periodic Table ofElements (F, Cl, Br, and I) and halogen-like species (e.g., that formstable monovalent anions) such as methanesulfonate (OMs),trifluoromethanesulfonate (OTf), toluenesulfonate (OTs), etc. Also, theterms “isolating” and “purifying” (and grammatical variations thereof)may be used interchangeably herein, but these terms are intended to havetheir art-recognized meanings, unless indicated otherwise.

The present invention concerns a polysilane compound, a “liquid silicon”ink composition containing the polysilane, methods for synthesizing thepolysilane and for making the ink composition, and methods of using thepolysilane and/or ink composition to make a semiconductor film. Ingeneral, the polysilane has the formulaH—[(AHR)_(n)(c-A_(m)H_(pm−2)R′_(rm))_(q)]—H, where each instance of A isindependently Si or Ge; each instance of R and R′ is independently H,—A_(a)H_(a+1)R² _(a) (where R² is H, aryl or substituted aryl), halogen,aryl or substituted aryl, but if q=0 and A is Si, R is not phenyl;(n+a)≧10 if q=0, q≧3 if n=0, and (n+q)≧6 if both n and q≠0; p is 1 or 2;(p+r)=2; and each instance of m is independently from 3 to 12. Thecomposition generally comprises the polysilane compound (preferablywhere R, R′ and [to the extent present] R² are H) and a solvent in whichthe polysilane is soluble.

Even further aspects of the invention concern methods of making apolysilane generally comprising the steps of (a) combining a silanecompound of the formula AH_(a)R¹ _(4−a), the formula A_(k)H_(g)R^(1′)_(h) and/or the formula c-A_(m)H_(pm)R^(1′) _(rm) with a catalyst of theformula R⁴ _(x)R⁵ _(y)MX_(z) (or an immobilized derivative thereof, orwhich may be synthesized in situ from the corresponding precursors) toform a poly(aryl)silane of the formulaH—[(AHR¹)_(n)-(c-A_(m)H_((pm−2))R^(1′) _(rm))_(q)]—H, where A, R¹, k, g,h, p, q, R^(1′), M, R⁴, R⁵, x, y, z, and X are as described herein, anda=2 or 3; (b) washing the poly(aryl)silane with a washing compositioncomprising water; and (c) contacting the poly(aryl)silane with anadsorbent sufficient to remove the metal from the poly(aryl)silane.Alternatively, the method may first form a polyarylsilane in accordancewith step (a), then include the steps of (b′) reacting thepolyarylsilane with (i) a halogen source and (optionally) a Lewis acid,or (ii) trifluoromethanesulfonic acid (HOTf), to form a halopolysilane;and (c′) reducing the halopolysilane with a metal hydride to form thepolysilane of the formula H—[(AH₂)_(n)-(c-A_(m)H_(pm−2))_(q)]—H.

The invention further relates to a method of making or forming asemiconductor film from the present ink composition, comprising thesteps of: (A) spin-coating or printing the composition onto a substrate(optionally, with simultaneous or immediately subsequent UVirradiation); (B) heating the composition sufficiently to form anamorphous, hydrogenated semiconductor; and (C) annealing and/orirradiating the amorphous, hydrogenated semiconductor sufficiently to atleast partially crystallize and/or reduce a hydrogen content of theamorphous, hydrogenated semiconductor and form the semiconductor film.

The invention, in its various aspects, will be explained in greaterdetail below with regard to exemplary embodiments.

An Exemplary Polysilane

In one aspect, the present invention relates to a polysilane having theformula H—[(AHR)_(n)(c-A_(m)H_(pm−2)R′_(rm))_(q)]—H, where each instanceof A is independently Si or Ge; each instance of R and R′ isindependently H, —A_(b)H_(b+1)R² _(b) (where R² is H, aryl orsubstituted aryl), halogen, aryl or substituted aryl, but if q=0 and Ais Si, R is not phenyl; (n+b)≧10 if q=0, q≧3 if n=0, and (n+q)≧6 if bothn and q≠0; p is 1 or 2; (p+r)=2; and each instance of m is independentlyfrom 3 to 12. In preferred embodiments, the polysilane has the formulaH—(AHR)_(n)—H (i.e., where q=0) or H-(c-A_(m)H_(2m−2))_(q)—H (i.e.,where n=0). However, as will be explained below (particularly withregard to FIG. 4), polysilanes having both cyclic blocks andlinear/branched chains are contemplated. Thus, “n” and “q*m” mayrepresent an average number of silicon and/or germanium atoms in thelinear polysilane and in the polycyclosilane, respectively, according toor calculated from the number average molecular weight (Mn) of thepolysilane. Furthermore, “n” may represent one or more blocks ofsubstantially linear or branched chains of silicon atoms in thepolysilane. Thus, in general, the polysilane may comprise a homopolymerof repeating —(—AHR—)—, —(—A_(k)H_(2k)—)— or -(c-A_(m)H_(2m−2))— units,or a block copolymer comprising one or more blocks of —(—AHR—)—,—(—A_(k)H_(2k)—)— and/or -(c-A_(m)H_(2m−2))— units, each of which mayinclude one or more such units in a given block.

A first exemplary polysilane has the formula H—(AHR)_(n)—H, where eachinstance of A is independently Si or Ge; each instance of R isindependently H, halogen, aryl, substituted aryl, or —A_(b)H_(b+1)R²_(b) (where R² is H, aryl or substituted aryl), but if A is Si, R is notphenyl; and (n+b)≧10. In general, the polysilane has a linear structure(i.e., where R is H, halogen, aryl when at least one A is Ge and arylother than phenyl when A is Si only, or substituted aryl), but branchedanalogs (i.e., where R is —A_(b)H_(b+1)R² _(b)) are possible. Generally,such branched analogs will be present in a mixture with one or morelinear polysilanes. In general, (n+b) and/or (n+qm) represent an averagenumber of silicon and/or germanium atoms in the product mixture, and inmost cases, that average number is less than or equal to about 50. Forexample, when the polysilane is linear, n≦50. However, under typicalconditions and/or using certain known catalysts and/or monomers, (n+b)is more typically ≦25 or 30.

In certain embodiments of the polysilane of H—(AHR)_(n)—H, R is H, Cl,or tolyl (preferably H), and A is Si. However, in other embodiments, atleast one A is Ge, and R may be phenyl. In such an embodiment, thepolygermasilane is essentially a random and/or statistical mixture ofpolysilanes, polygermanes and polygermasilanes containing a proportionor ratio of germanium-to-silicon atoms that substantially corresponds tothe proportion or ratio of the germanium monomer to silicon monomer inthe mixture of starting materials, as may be more fully explained below.

In another aspect, the polysilane has the formulaH-(c-A_(m)H_(2m−2))_(q)—H, where q≧3 (e.g., from 3 to 10); and eachinstance of m is independently from 3 to 12. In particular, m isgenerally from 5 to 8, and typically, most instances (e.g., more than50%, 70% or 80%) of m will predominantly be 5.

The structure and nature of the present poly(aryl)silanes andpoly(halo)silanes may be better understood with reference to someexemplary methods for their synthesis.

An Exemplary Method of Making Polyarylsilanes

In general, poly- and oligo-hydrosilane and -hydrogermane compounds forsemiconductor inks can be synthesized by dehydrocoupling ofarylhydrosilanes and/or arylhydrogermanes (R¹AH₃ or R¹ ₂AH₂, where R¹ isaryl and A=Si or Ge, to form linear, branched, cyclic, and/or cagedarylhydrosilanes and/or arylhydrogermanes), followed by Lewisacid-catalyzed cleavage of the aryl groups and hydride reduction toyield linear, branched, cyclo-, and/or caged polysilanes, polygermanesor polysilagermanes. This aspect of the invention focuses ondehydrocoupling of arylhydrosilanes and/or arylhydrogermanes (R¹AH₃,where R¹ is aryl and A=Si or Ge).

Dehydrocoupling of arylhydrosilanes using titanium (Ti), zirconium (Zr),hafnium (Hf), neodymium (Nd) and uranium (U) catalysts is known (see,e.g., T. D. Tilley, Acc. Chem. Res. 1993, vol. 26, pp. 22-29; V. K.Dioumaev and J. F. Harrod, J. Organomet. Chem. vol. 521, pp. 133-143;and Q. Wang and J. Y. Carey, Can. J. Chem. vol. 78 [2000], pp.1434-1440). In part, the present invention relates to use of thisapproach to synthesize novel polyarylhydrosilanes, -germanes and/or-silagermanes, and to an improved method for synthesizingpolyarylhydrosilanes, -germanes and/or -silagermanes that eliminates themetal catalyst to a significantly greater degree than alternativeapproaches, thereby significantly improving the stability ofsubsequently-produced polyhydrosilanes, -germanes and/or -sila-germanes.

Thus, in one aspect, the present invention relates to a method of makinga polysilane, comprising (a) combining a silane compound of the formulaAH_(a)R¹ _(4−a), the formula A_(k)H_(g)R^(1′) _(h) and/or the formulac-A_(m)H_(pm)R^(1′) _(rm) with a catalyst of the formula R⁴ _(x)R⁵_(y)MX_(z) (or an immobilized derivative thereof, or which can besynthesized in situ from corresponding precursors) to form apoly(aryl)silane of the formula H—[(AHR¹)_(n)-(c-A_(m)H_(pm−2))R^(1′)_(rm))_(q)]—H, where each instance of A is independently Si or Ge, a=2or 3, and each instance of R¹ and R^(1′) is independently aryl,substituted aryl, or —A_(b)H_(b+1)R² _(b) (where R² is aryl orsubstituted aryl); (n+b)≧10 if q=0, q≧3 if n=0, and (n+q)≧6 if both nand q≠0; k is an integer of from 2 to 12, g≧2 and (g+h)=2k+2; p is 1 or2, m is an integer of from 3 to 12, p is 1 or 2, and r is 0 or 1; R^(1′)is the same as R′, except that when R¹ is —A_(b)H_(b+1)R² _(b), R^(1′)may be H; M is a metal selected from the group consisting of Ti, Zr andHf, x=1 or 2, y=1, 2 or 3, z=0, 1 or 2, 3≦(x+y+z)≦8, each of the xinstances of R⁴ is independently a substituted or non-substitutedcyclopentadienyl, indenyl, fluorenyl, siloxyl, germoxyl, hydrocarbyl,hydrocarbyloxy, hydrocarbylamino, or hydrocarbylsulfido ligand; each ofthe y instances of R⁵ is independently a substituted or non-substitutedhydrocarbyl, hydrocarbyloxy, hydrocarbylamino, hydrocarbylsulfido,silyl, (per)alkylsilyl, germyl, (per)alkylgermyl, hydride, phosphine,amine, sulfide, carbon monoxide, nitryl, or isonitryl ligand, and X is ahalogen; (b) washing the poly(aryl)silane with a washing compositioncomprising water; and (c) contacting the poly(aryl)silane with anadsorbent sufficient to remove the metal (i.e., from the catalyst) fromthe poly(aryl)silane.

In the first exemplary embodiment of the present method, the silanecompound has the formula AH_(a)R¹ _(4−a). In preferred implementationsof this embodiment, A is Si, R¹ is phenyl or tolyl, and/or a is 3.However, compounds of the formula A_(k)H_(g)R^(1′) _(h) (particularlywhere k is an integer of at least 2, g=k, [k+2], 2k or [2k+2], and h=0,2, or k) are likely to be present in the dehydrocoupling reactionmixture. As a result, the present method contemplates use of compoundsof the formula A_(k)H_(g)R^(1′) _(h) for making poly(aryl)silanes.

Preferably, the metal M in the dehydrocoupling catalyst is Zr or Hf.These metals tend to provide a sufficient balance betweendehydrocoupling rate or activity, poly(aryl)silane molecular weight andcontent of cyclosilane by-products (e.g., Hf generally produces a higherproportion of linear polysilane products than Zr). In variousembodiments, x is 2 and R⁴ is cyclopentadienyl (Cp),permethyl-cyclopentadienyl (Cp*), indenyl or fluorenyl (Fl). Having atleast one bulky or substituted cyclopentadienyl ligand (e.g., Cp*,indenyl or fluorenyl) tends to promote dehydrocoupling by reducing atendency of the catalyst to dimerize, but the catalyst is not at allrequired to have such a ligand. Also, in various embodiments, y is 2 andR⁵ in the dehydrocoupling catalyst is H, C₁-C₆ alkyl, C₆-C₁₂ aryl, SiR²₃, or Si(SiR² ₃)₃, where R² is H or C₁-C₄ alkyl. Such ligands arebelieved to promote metathesis of Si—H or Ge—H bonds in the startingsilane compound.

Generally, the washing composition in this embodiment of the presentmethod comprises deionized water or dilute aqueous acid. For example,the aqueous acids suitable for use in the present method generallyinclude the mineral acids and their equivalents, such as hydrochloricacid, hydrobromic acid, trifluoroacetic acid, andtrifluoromethanesulfonic acid. Preferably, the aqueous acid compriseshydrochloric acid. The dilution factor for the washing composition maybe from 1:1 to 1:1000 (concentrated mineral acid to water), generally byvolume. For example, the dilute aqueous acid may comprise from 0.1 to 10vol. % (e.g., from 1 to 5 vol. %) of conc. HCl in deionized water. In apreferred implementation, the present washing step comprises washing thepoly(aryl)silane one or more times with dilute aqueous acid, followed bywashing the acid-washed poly(aryl)silane one or more times with water.

In general, to further remove the metal from the poly(aryl)silane, asolution of the poly(aryl)silane in a suitable organic solvent(typically the washed poly[aryl]silane) is contacted with the adsorbentfor a length of time sufficient for the adsorbent to adsorb the metalfrom the catalyst. The adsorbent generally comprises a chromatographygel or finely divided silicon and/or aluminum oxide that issubstantially unreactive with the polyarylsilane. Examples of suitableadsorbents include silica gel, alumina, FLUORISIL, and CELITE. In oneembodiment, such contacting comprises passing the poly(aryl)silanethrough a column packed with the adsorbent. Alternatively, a solution ofthe poly(aryl)silane may be mixed with the adsorbent for a length oftime sufficient for the adsorbent to adsorb the metal/catalyst from thesolution. The adsorbent is generally removed from the adsorption mixtureby conventional filtration.

FIG. 1 shows a first exemplary scheme illustrating dehydrocoupling ofPhSiH₃, followed by Lewis acid-catalyzed chlorination and reduction.Dehydrocoupling of PhSiH₃ generally forms polyphenylsilane 20 and arelatively small proportion of cyclic silane compounds such ascyclopentaphenylsilane (c-(SiHPh)₅ 25). Although the polyphenylsilane 20may be separated and/or isolated from the cyclopentaphenylsilane and/orother cyclic silane compounds, the cyclic silane compounds such asc-(SiHPh)₅ 25 generally do not affect subsequent steps in the synthesisof polysilanes (see, e.g., the formation of semiconducting filmsdiscussed below). The dehydrocoupling reaction evolves hydrogen gas, andthus, tends to be irreversible if the hydrogen gas is removed from thedehydrocoupling reaction vessel. Generally, thepolymerization/dehydrocoupling reaction time is from a few hours (e.g.,3, 4, 6 or more hours) to a few days (e.g., 3, 4 or 5 days). Thereaction mixture may be formed by dropwise addition of the monomer to asolution of the catalyst, or by mixing the catalyst directly with themonomer. In fact, neat solutions of silane/germane monomer and catalysttend to provide higher molecular weights (e.g., number average molecularweights, or Mn) of polyarylsilane 20. The reaction temperature is alsokept relatively low (e.g., from about 0 to about 30° C.), generally topromote higher polyarylsilane 20 molecular weights and/or to reduce theamount of cyclic silane compound. However, in some cases (e.g., when asterically crowded catalyst and/or monomer is/are used), a highertemperature may be advantageous for increasing the reaction rate.

As shown in FIG. 1, the dehydrocoupling catalyst Cp₂ZrPh₂ may begenerated in situ from a zirconocene halide (e.g., Cp₂ZrCl₂) and analkyl, aryl or peralkylsilyl metal reagent (e.g., PhMgBr, which can alsobe generated in situ in accordance with known techniques).Dehydrocoupling catalysts include complexes of Ti, Zr, and/or Hf, in anoxidation state of +4, +3, and/or +2, and having a general formula R⁴_(x)R⁵ _(y)MX_(z), where M=Ti, Zr, or Hf; x=1 or 2, y=2 or 3, z=0, 1 or2, 3≦(x+y+z)≦8 (which may depend on the coordination sites available onM, as is known in the art), each of the x instances of R⁴ isindependently a substituted or non-substituted cyclopentadienyl,indenyl, fluorenyl, siloxyl, germoxyl, hydrocarbyl, hydrocarbyloxy,hydrocarbylamino, or hydrocarbylsulfido ligand; each of the y instancesof R⁵ is independently a substituted or non-substituted hydrocarbyl,hydrocarbyloxy, hydrocarbylamino, hydrocarbylsulfido, silyl, germyl,hydride, phosphine, amine, sulfide, carbon monoxide, nitryl, orisonitryl ligand; and X is a halogen (e.g., Cl, Br, OTf, ClO₄, etc.).

Further, the metal M, or one or more of the x instances of R⁴, yinstances of R⁵ or z instances of X, can be independently bound to asilica, alumina, or polymer surface rendering the catalystheterogeneous. The polymer is typically a hydrocarbon polymer, such aspolyethylene, polypropylene, polystyrene, a polyethylene-polypropyleneor polyethylene-polystyrene copolymer, etc.

Alternative catalysts can include any conventional dehydrocouplingcatalyst, especially those containing a Group 4 element. For example, anHf analog of the Zr catalyst in FIG. 1 will generally reduce the amountof cyclic silane compounds produced. Also, as mentioned above,metallocene catalysts containing a relatively bulky ligand, such asCpCp*Zr(SiMe₃)Ph, may provide higher molecular weight polyphenylsilanes(e.g., having a Mn as high as 5000 Daltons [i.e., n≈25-45], whereas theMn of the polyphenylsilane 20 produced using Cp₂ZrPh₂ is generallyaround 1200 Daltons [i.e., n≈10-12]). Use of a sterically crowdedcatalyst like CpCp*Zr(SiMe₃)Ph is expected to produce a higher viscositypolysilane ink composition.

The starting material(s) and/or substrates generally include silicon andgermanium compounds of the general formula R¹AH₃ or R¹ ₂AH₂, where A isSi or Ge, and R¹ is aryl or substituted aryl. Use of tolylsilane(CH₃C₆H₄SiH₃) as a monomer instead of phenylsilane (PhSiH₃) may beadvantageous for subsequent steps in the polysilane synthesis.Tolylsilane (and oligomers thereof) are generally easier to chlorinate(e.g., cleave the C—Si bond with HCl and a Lewis acid such as AlCl₃),thereby presumably reducing aromatic impurities in any subsequentlysynthesized polysilane.

Typical conditions for dehydrocoupling reaction include a temperature ofabout ambient or room temperature, a pressure of about atmosphericpressure (or about 1 atm) of inert gas under dynamic conditions (e.g.,in a reaction vessel having somewhat free gas out-flow, such as a gasbubbler, generally to allow escape of evolved hydrogen gas). The typicalcatalyst loading may be >1 mol % (e.g., from 1 to 10 mol %, 2 to 5 mol%, or any range of values therein, relative to the molar quantity ofmonomer) for dehydrocoupling of arylsilanes and arylgermanes.

The adsorbing step in the present method is generally used to remove themetal of the catalyst (e.g., Zr in FIG. 1) from the polyphenylsilane 20.Conventional chromatography methods using gels, such as FLORISIL, andother gels like silica, alumina, and CELITE are generally suitable.Alternatively, the gel is added to a polyphenylsilane 20 solution andstirred (generally for a length of time sufficient to remove some orsubstantially all of the metal from the solution), then the gel isgenerally removed by filtration. Contacting a chromatography gel with asolution of the polyphenylsilane 20 can be substituted by simply passingthe solution of polyphenylsilane 20 through a thick pad of the gel.

The solvents used in the procedure are not limited. Cyclohexane,toluene, and diethyl ether are generally preferred, although any solventor mixture of solvents with relatively low boiling points (e.g., ≦100°C., ≦80° C., or ≦60° C.), compatible with polysilanes, are suitable.

FIG. 2 shows a second exemplary scheme illustrating dehydrocoupling ofPhSiH₃ and PhGeH₃, followed by chlorination and reduction. Generally, amixture of arylsilane (e.g., PhSiH₃) and arylgermane (PhGeH₃) aredehydrocoupled using a diaryl-, bis(peralkylsilyl)-,aryl(peralkylsilyl)-, dialkyl- or alkyl(peralkylsilyl) metallocenecatalyst such as Cp₂ZrPh₂ to provide a polyphenylsilagermane 110 of theformula H—(SiHPh)_(n)(GeHPh)_(m)—H, where (n+m)≧10. In thepolyphenylsilagermane 110 product, n and m generally represent a randomand/or statistical mixture corresponding to the molar ratio of PhSiH₃ toPhGeH₃ in the dehydrocoupling reaction mixture. Thus, m may be anywherefrom 1 to (n−1), but more typically, the molar ratio of PhSiH₃ to PhGeH₃is anywhere from 1:1 to 20:1, and thus, m will typically be an integerof from 1 to n. The product mixture containing polyphenylsilagermane 110may also include cyclic and linear/branched polyphenylsilanes and-germanes. No significant and/or detectable heterocoupling may occur insuch cyclic byproducts in the synthetic approach of FIG. 2.

An Exemplary Method of Making Polysilanes

Cleavage of aryl groups bound to Si or Ge, and reduction of siliconand/or germanium halides and pseudo-halides are generally disclosed in,e.g., U.S. patent application Ser. Nos. 10/789,317, 10/949,013,10/950,373 and 10/956,714, respectively filed on Feb. 27, 2004, Sep. 24,2004, Sep. 24, 2004, and Oct. 1, 2004, the relevant portions of whichare incorporated herein by reference. Typically, and as shown in FIGS. 1and 2, this cleavage reaction is conducted with HCl and AlCl₃. However,as is also known, a conventional chlorination-based cleavage reactioncan be substituted with HBr to obtain a polybromosilane, or with TfOH toobtain a poly(trifluoromethanesulfonyl)silane. Thus, the presentinvention also relates to the combination of (1) catalyticdehydrocoupling as described above and (2) the cleavage and reductionprocesses described herein, to synthesize polyhydrosilanes, -germanesand/or -silagermanes.

Thus, in another aspect, the present invention concerns a method ofmaking a polysilane, comprising the steps of (a) combining a silanecompound of the formula AH_(a)R¹ _(4−a), the formula A_(k)H_(g)R^(1′)_(h) and/or the formula c-A_(m)H_(pm)R^(1′) _(rm) with a catalyst of theformula R⁴ _(y)R⁵ _(y)MX_(z) (or an immobilized derivative thereof) toform a polyarylsilane of the formula H—[(AHR¹)_(n)(c-A_(m)H_((pm−2))_(R) ^(1′) _(rm))_(q)]—H as described above, where each instance of A isindependently Si or Ge, a=2 or 3, each instance of R′ and R^(1′) isindependently aryl, substituted aryl, or —A_(b)H_(b+1)R_(b) (where R isaryl or substituted aryl); (n+b)≧10 if q=0, q≧3 if n=0, and (n+q)≧6 ifboth n and q≠0; p is 1 or 2; k is an integer of from 2 to 12, g≧2 and(g+h)=2k+2; each instance of m is independently from 3 to 12; M is ametal selected from the group consisting of Ti, Zr and Hf; x=1 or 2;y=1, 2 or 3; z=0, 1 or 2; 3≦(x+y+z)≦8; each of the x instances of R⁴ isindependently a substituted or non-substituted cyclopentadienyl,indenyl, fluorenyl, siloxyl, germoxyl, hydrocarbyl, hydrocarbyloxy,hydrocarbylamino, or hydrocarbylsulfido ligand; each of the y instancesof R⁵ is independently a substituted or non-substituted hydrocarbyl,hydrocarbyloxy, hydrocarbylamino, hydrocarbylsulfido, silyl, germyl,hydride, phosphine, amine, sulfide, carbon monoxide, nitryl, orisonitryl ligand; and X is a halogen; (b) reacting the polyarylsilanewith (i) a halogen source and (optionally) a Lewis acid or (ii)trifluoromethanesulfonic acid (HOTf), to form a halopolysilane; and (c)reducing the halopolysilane with a metal hydride to form a polysilane ofthe formula H—[(AH₂)_(n)(c-A_(m)H_(pm−2))_(q)]—H.

Generally, the method comprises combining a silane compound of theformula AH_(a)R¹ _(4−a) with a catalyst of the formula R⁴ _(x)R⁵_(y)MX_(z) to form a polyarylsilane of the formula H—(AHR¹)_(n)—H.However, as described above, compounds of the formula A_(k)H_(g)R^(1′)_(h) (particularly where k is an integer of at least 2, g=2, [k+2], 2kor [2k+2], and h=0, 2 or k, depending on the structure of the silanestarting compound) are likely to be present in the dehydrocouplingreaction mixture. As a result, the present method contemplates use ofcompounds of the formula A_(k)H_(g)R^(1′) _(h) for makingpolyarylsilanes. Also, in certain embodiments, the method comprisesreacting the polyarylsilane with the halogen source and the Lewis acid,wherein the Lewis acid comprises a compound of the formula M³ _(v)X²_(w), where M³ comprises a member selected from the group consisting oftransition metals and Group IIIA elements; v is 1 or 2; X² comprises ahalogen; and w is any integer up to the number of ligand binding sitesavailable on the v instances of M³. In a preferred embodiment, M³comprises Al, and X² is Cl or Br (e.g., Cl, as shown in FIGS. 1-2).

In further embodiments of the present method, the metal hydridecomprises a compound of the formula M¹ _(a)M² _(b)H_(c)R⁶ _(d), where M¹and M² are independently first and second metals, each R⁶ in the metalhydride compound is independently a ligand bound to at least one of M¹and M² by a covalent, ionic or coordination bond, at least one of a andb is at least 1, c is at least 1, and d is 0 or any integer up to oneless than the number of ligand binding sites available on the (a+b)instances of M¹ and M². In certain implementations, the metal hydridecomprises a member of the group consisting of lithium aluminum hydride(LAH, as shown in FIGS. 1-2), calcium aluminum hydride, sodiumborohydride, aluminum hydride, gallium hydride, and aluminumborohydride.

Referring to FIGS. 1-2, the procedure for Lewis acid-catalyzedhalogenation (e.g., treatment or reaction of polyarylsilane 20 orpolyarylsilagermane 110 with HCl and AlCl₃ in an inert organic solventsuch as cyclohexane) is largely as described in U.S. patent applicationSer. No. 10/789,317. However, exemplary variations of the procedureinclude a halogenation (e.g., chlorination) by bubbling HX gas (e.g.,dry HCl) through a solution of polyarylsilane 20 or polyarylsilagermane110 and Lewis acid for a length of time of from 30 min. to about 6 hoursto form polychlorosilane 30 or polychlorosilagermane 120, respectively,and reduction using a metal hydride reducing reagent (not limited tolithium aluminum hydride [LAH], although LAH as shown in FIGS. 1 and 2is a preferred metal hydride reducing reagent) for a length of time offrom about 1 hour, 2 hours or 4 hours to about 8, 12, or 16 hours (e.g.,overnight). Other exemplary metal hydride reducing agents are disclosedin U.S. patent application Ser. Nos. 10/789,317, 10/949,013, 10/950,373and 10/956,714, the relevant portions of which are incorporated hereinby reference. Also, the reagent addition sequence preferably comprisesadding a solution of metal hydride (e.g., LAH) in an inert organicsolvent (e.g., dry diethyl ether) to a stirred solution ofpolychlorosilane 20 or polychlorosilagermane 120. Workup is generally asdescribed in U.S. patent application Ser. Nos. 10/789,317, 10/949,013,10/950,373 and 10/956,714, the relevant portions of which areincorporated herein by reference.

A Second Exemplary Method for Making Oligo- and/or Polysilanes

In another aspect, the present invention concerns a method of makingoligo- and/or polysilanes that includes simply a dehydrocoupling step(e.g., dehydrocoupling of perhydrosilanes and/or perhydrogermanes; e.g.,linear, branched, cyclo-, or caged hydrosilanes and/or hydrogermanes),such as the exemplary reaction scheme of FIG. 3. FIG. 3 shows anexemplary scheme illustrating dehydrocoupling of cyclo-Si₅H₁₀ 15 to formpoly(cyclopentasilane) 200. Generally, the same dehydrocoupling catalyst(e.g., α-fluorenyl-α,α-dimethylsilylfluorenyl dibutylzirconium, or[Fl₂SiMe₂]ZrBu₂, generated in situ as shown in FIG. 3) as describedabove may be used for dehydrocoupling cyclosilanes. For dehydrocouplingof c-Si₅H₁₀, typical catalyst loading may be <0.1 mol % (e.g., from0.0001 to 0.1 mol %, 0.001 to 0.05 mol %, or any range of valuestherein), relative to the amount of monomer (e.g., C-Si₅H₁₀).

Thus, the present invention further concerns a method of making anoligo- and/or polysilane, comprising (1) combining a silane compound ofthe formula c-A_(m)H_(pm) and/or the formula A_(k)H_(2k+2) with acatalyst of the formula R⁴ _(x)R⁵ _(y)MX_(z) (or an immobilizedderivative thereof, or which may be synthesized in situ fromcorresponding precursors) to form a polysilane of the formulaH—(A_(k)H_(2k))_(q′)-(c-A_(m)H_(pm−2))_(q)—H, where each instance of Ais independently Si or Ge, q′+q≧3, p is 1 or 2, k is an integer of from2 to 12, m is an integer of from 3 to 12, and M, x, y, z, R⁴, R⁵, and Xare as described above; (2) washing the polysilane with a washingcomposition comprising water; and/or (3) contacting the polysilane withan adsorbent sufficient to remove the metal from the polysilane.

In further embodiments of the approach exemplified in FIG. 3, A isindependently Si or Ge, q≧3, p is 1 or 2, and/or m is from 3 to 12(preferably from 5 to 8). In addition, linear and/or branched silanes ofthe general formula A_(k)H_(2k+2) (where k is from 1 to 12, preferablyfrom to 10 [e.g., for homogeneous synthesis] or from 1 to 4 [e.g., forheterogeneous synthesis]) may be added to the dehydrocoupling reactionmixture to form polysilanes of the formulaH—[(AHR*)_(n)]_(t)-(c-A_(m)H_(pm−2))_(q)]-H, where R* is H or—A_(b)H_(2b+1)R_(b) (preferably H), each of the t instances of n areindependently from 1 to 12 (preferably from 3 to 12, more preferablyfrom 5 to 10), each of the t*n instances of b are independently from 1to 6 (preferably from 1 to 4), t*(n+b)≧4 (preferably ≧6 and morepreferably ≧10), and m, p and q are as described above.

A Third Exemplary Method for Making Oligo- and/or Polysilanes

In another aspect, the present invention concerns oligo- and/orpolysilanes containing both linear and cyclic portions and a method ofmaking the same, based on catalytic dehydrocoupling (e.g.,dehydrocoupling of [aryl]silanes and/or [aryl]germanes with cyclosilanesand/or cyclogermanes), such as the exemplary reaction scheme of FIG. 4.FIG. 4 shows an exemplary scheme illustrating dehydrocoupling ofphenylsilane (PhSiH₃) with cyclo-Si₅H₁₀ 15 to form block copolymer orlinear/branched poly(phenylsila)(cyclopentasilylene) 320. Generally, thesame dehydrocoupling catalyst (e.g., bis[cyclopentadienyl]diphenylzirconium or [Fl₂SiMe₂]ZrBu₂, as shown in FIGS. 1-3) asdescribed above may be used for dehydrocoupling arylsilanes withcyclosilanes. Linear or branched perhydrosilanes can be substituted foror added to the cyclosilanes, to provide a greater degree of branchingor to possibly increase the average number of silicon atoms in thepolymer/oligomer. Also, cyclosilanes with an exocyclic silyl group(e.g., cyclo-[(SiPhH)₄SiH]—[SiH₃]) are also contemplated for use in theinvention, and this are encompassed by the formula “c-A_(m)H_(pm).” Thesubscript “n” generally represents an average of the number of siliconatoms in the polysilane, and in this aspect of the invention, furtherrepresents two or more blocks of substantially linear or branchedsilicon chains in the polysilane.

Thus, the present invention further concerns a method of making anoligo- and/or polysilane, comprising (I) combining a silane compound ofthe formula c-A_(m)H_(pm) and/or the formula A_(k)H_(2k+2) with a silanemonomer of the formula AH₃R¹ and a catalyst of the formula R⁴ _(x)R⁵_(y)MX_(z) (or an immobilized derivative thereof, or which may besynthesized in situ from corresponding precursors) to form a block orbranched polyarylsilane of the formulaH—[(AHR¹)_(n)]_(u)—(A_(k)H_(2k))_(q′)-(c-A_(m)H_(pm−2))_(q)—H, whereeach instance of A, R¹ and n are as described herein, u=(q′+q) or(q′+q)±1, q′+q≧3, p is 1 or 2, k is an integer of from 2 to 12, m is aninteger of from 3 to 12, and M, x, y, z, R⁴, R⁵, and X are as describedabove; (II) reacting the block or branched poly(aryl)silane with (i) ahalogen source and (optionally) a Lewis acid or (ii)trifluoromethanesulfonic acid (HOTf), to form a block or branchedhalopolysilane; and (c) reducing the block or branched halopolysilanewith a metal hydride to form a polysilane of the formulaH—[(AH₂)_(n)]_(u)—(A_(k)H_(2k))_(q′)-(c-A_(m)H_(pm−2))_(q)—H. In furtherembodiments of the approach exemplified in FIG. 4, A is Si, q′ is 0, pis 2, and/or m is from 5 to 8 (preferably 5 or 6).

An Exemplary Polysilane Composition and/or Semiconductor Ink

A further aspect of the present invention relates to a composition,comprising the present polysilane and a solvent in which the polysilaneis soluble. Preferably, the solvent is one that is easily removed(and/or substantially completely removable) from the composition, andmay be selected from the group consisting of linear alkanes,cycloalkanes, polycycloalkanes, (cyclic) siloxanes and fluoroalkanes.The (cyclic) siloxane solvents are generally those that are liquid atambient temperatures (e.g., 15-30° C.), and may be selected fromsiloxanes of the formula (R₃Si)(OSiR₂)_(p)(OSiR₃) and cyclosiloxanes ofthe formula (SiR′₂O)_(q), where p is from 0 to 4, q is from 2 to 6(preferably from 3 to 5), each R and R′ is independently H, C₁-C₆ alkyl,benzyl or phenyl substituted with from 0 to 3 C₁-C₄ alkyl groups(preferably R and R′ are methyl). The fluoroalkane may be selected fromC₃-C₈ fluoroalkanes substituted with from 1 to (2 m+2) fluorine atomsand that are liquid at ambient temperatures, where m is the number ofcarbon atoms in the fluoroalkane. More preferably, the solvent may beselected from the group consisting of C₆-C₁₂ monocycloalkanes andC₁₀-C₁₄ di- or tricycloalkanes (e.g., decalin). Preferably, the solventis a C₆-C₁₀ cycloalkane (e.g., cyclohexane, cycloheptane, cyclooctane,etc.).

In the present ink composition, the polysilane is present in an amountof from about 0.5 to about 50%, preferably 5 to about 30% (morepreferably from about 10 to about 20%) by weight or by volume. Ofcourse, when the polysilane is in a liquid phase at room temperature, itmay be used neat if its viscosity (and/or other physical and/or chemicalproperties) are suitable for printing and/or coating processes. Suitableink formulations are disclosed in U.S. patent application Ser. Nos.10/789,274, 10/789,317, 10/949,013, 10/950,373 and 10/956,714,respectively filed on Feb. 27, 2004, Feb. 27, 2004, Sep. 24, 2004, Sep.24, 2004, and Oct. 1, 2004, the relevant portions of which areincorporated herein by reference. In the present case, the presentpolysilane may be substituted in part or entirely for the (cyclo)silaneand/or hetero(cyclo)silane described in U.S. patent application Ser.Nos. 10/789,274, 10/789,317, 10/949,013, 10/950,373 and 10/956,714.

An Exemplary Method for Making a Semiconductor Film

A further aspect of the invention relates to a method of forming asemiconductor film from the present composition, comprising the steps of(A) spin-coating or printing the composition onto a substrate(optionally, with simultaneous or immediately subsequent UVirradiation); (B) heating the composition sufficiently to form anamorphous, hydrogenated semiconductor; and (C) annealing and/orirradiating the amorphous, hydrogenated semiconductor sufficiently to atleast partially crystallize and/or reduce a hydrogen content of theamorphous, hydrogenated semiconductor and form the semiconductor film.Preferably, the method of forming a semiconductor film comprisesprinting (e.g., inkjetting) the composition onto a substrate (e.g., aconventional silicon wafer, glass plate, ceramic plate or disc, plasticsheet or disc, metal foil, metal sheet or disc, or laminated or layeredcombination thereof, any of which may have an insulator layer such as anoxide layer thereon), and/or irradiating the amorphous, hydrogenatedsemiconductor with a sufficient dose of laser radiation to crystallizeand/or electrically activate the amorphous, hydrogenated semiconductorand form the semiconductor film.

In the present method, it may be advantageous to irradiate thecomposition during deposition onto the substrate. Generally, as long asthe ink composition is irradiated reasonably shortly after deposition(e.g., spincoating), it has a viscosity sufficient to form a film orlayer on the substrate that does not bead up, disproportionate orotherwise substantially adversely affect the uniformity of asubsequently formed semiconductor film. Such irradiation of a coatedand/or printed film prior to curing may provide further control of thefilm drying process, e.g., by increasing the viscosity of the inkcomposition after deposition. For example, the present composition(e.g., prior to deposition) may have a viscosity of from 2.5 to 20 cP, 3to 12 cP, or any range of values therein.

Suitable methods for forming a semiconductor film are disclosed in U.S.patent application Ser. Nos. 10/789,274, 10/949,013, 11/084,448 and11/203,563, respectively filed on Feb. 27, 2004, Sep. 24, 2004, Mar. 18,2005 and Aug. 11, 2005, the relevant portions of which are incorporatedherein by reference. In the present case, the present polysilane inkcomposition may be substituted in part or entirely for the (cyclo)silaneand/or hetero(cyclo)silane ink composition described in U.S. patentapplication Ser. Nos. 10/789,274, 10/949,013, 11/084,448 and 11/203,563.The first heating and/or annealing step may comprise (i) “soft” curingthe printed or coated ink composition, generally at a temperature of≦200° C., ≦150° C., ≦120° C. or any maximum temperature in that range,sufficiently to remove volatile components (e.g., solvent, volatilesilane compounds, etc.) and/or to further polymerize the silane film,and (ii) “hard” curing the film, generally at a temperature of ≦600° C.,≦500° C., ≦450° C. or any maximum temperature in that range,sufficiently to form a hydrogenated, amorphous silicon film. Generally,to obtain the most commercially valuable electrical activity and/orcharacteristics, the film is crystallized by heating in a furnace orirradiating with a dose of laser radiation sufficient to partly orsubstantially completely crystallize the hydrogenated, amorphous siliconfilm (e.g., form a polycrystalline silicon film). The use of laserradiation for crystallization advantageously includes a furtherannealing step to reduce the hydrogen content of the hydrogenated,amorphous silicon film prior to laser irradiation.

The described polysilanes and polysilane inks may also be used for theformation of doped silicon films. For example, an ink compositioncomprising the present polysilane may be printed or coated (optionally,with simultaneous or immediately subsequent UV irradiation) onto asubstrate, converted to an amorphous or (partially) polycrystallinesilicon film and subsequently doped, e.g., by conventional ionimplantation or other doping technique such as ion showering or use ofconventional spin-on-dopants (and optionally, subsequent annealing).Alternatively, the present ink composition may be further mixed with oneor more dopants of the formula D_(a)H_(b) and/or D_(a)R⁶b′ (where D isSb, As, P or B; a is from 1 to 20; b is from 0 to 26; each of the b′instances of R⁶ is independently H, alkyl, aryl, aralkyl or AR^(2′) ₃,where R^(2′) is hydrogen, alkyl, aryl, aralkyl or A_(y)H_(2y+1) [e.g.,where 1≦y≦4, such as SiH₃ and Si(SiH₃)₃]; and b′ is an integercorresponding to the number of binding sites available on the ainstances of D) and/or one or more doped silane and/or germane compoundsof the formula (R^(2′) ₃A)_(r)A_(c)(DR⁶ ₂)_(s) (where D, a, R^(2′) andR⁶ are as described for the dopant; c is 1 to 4, r+s=2c+2, and s≧1[preferably s≧3]) in an amount sufficient to provide a predetermineddoping level or concentration and/or electrical characteristics in theelectrically active film within a predetermined range of values. Suchdopants, doped silanes and germanes, and others are disclosed in U.S.patent application Ser. No. 10/949,013, filed on Sep. 24, 2004, therelevant portions of which are incorporated herein by reference.

Coating may comprise spin coating, inkjetting, dip-coating,spray-coating, slit coating, extrusion coating, or meniscus coating theink composition onto a substrate. Preferably, coating comprises spincoating. Printing may comprise inkjetting or gravure, flexographic,screen or offset printing the ink in locations on the substratecorresponding to active transistor regions. After drying and/or heatingthe printed/coated film to remove any solvents and/or cure the film, andoptionally irradiating the film (e.g., to fix the silanes to thesubstrate and/or to each other), the resulting semiconductor film/layergenerally has an amorphous morphology, and before further processing, itis generally annealed (e.g., to reduce the hydrogen content of thepolysilane) and crystallized (e.g., by heating or by laser irradiation;see, e.g., U.S. patent application Ser. Nos. 10/950,373 and 10/949,013,each of which was filed on Sep. 24, 2004, the relevant portions of whichare incorporated herein by reference). In many cases, suchcrystallization will also activate at least some of the added dopant.

One may also induce crystallization (in addition to activating some orall of the dopant) using conventional metal-promoted(re)crystallization. Suitable metal-based crystallization promoters andprocesses for their use in crystallizing an amorphous semiconductor film(e.g., as formed from semiconductor nanoparticles containing Si and/orGe) may be disclosed in application Ser. No. 10/339,741, filed Jan. 8,2003, U.S. Pat. No. 7,078,276, the relevant portions of which areincorporated herein by reference.

EXPERIMENTAL EXAMPLES General Procedures

Standard Schlenk techniques were used for all synthesis and samplemanipulations. A grease-free reaction setup utilizing threaded Teflonstopcocks was generally used to reduce contamination. Glassware wasdried overnight at 120° C. in an oven before use. ¹H NMR and ²⁹Si NMRwere measured by Acorn INC using d₆-benzene or d₁₂-cyclohexane assolvent. The molecular weight of polyphenylsilane was analyzed byScientific Polymer Products, Inc., using Phenomenex phenogel columns.Elemental analyses were carried out by Desert Analytics.

Solvents and reagent purification. Toluene was purified by shaking twicewith cold conc. H₂SO₄ (100 ml acid per L solvent), once or twice withwater, once with aqueous 5% NaHCO₃, and again with water.Carbonyl-containing impurities were then removed by percolation througha Celite column impregnated with 2,4-dinitrophenylhydrazine, phosphoricacid and H₂O. The washed toluene was then dried over 4 Å molecularsieves overnight, and was distilled fresh to remove high boiling pointresidue.

Cyclohexane was first washed with conc. H₂SO₄ until the washings werecolorless, followed by washing with alkaline potassium permanganateuntil the purple color of potassium permanganate did not change.Carbonyl-containing impurities were then removed by percolation througha Celite column impregnated with 2,4-dinitrophenylhydrazine, phosphoricacid and H₂O. The washed cyclohexane was then dried with activated 4 Åmolecular sieves overnight and distilled over sodium (under argon).

Inhibitor-free diethyl ether was passed through a column of activatedalumina (100 g Al₂O₃/1 L of ether), dried over lithium aluminum hydride(LAH) overnight, and freshly distilled under argon. DME(1,2-dimethoxyethane) was purified using the same method as forpurifying ether.

PhSiH₃ (Gelest) was dried over 4 Å molecular sieves overnight, and thendistilled under argon. AlCl₃ was purified by sublimation at 160° C.under vacuum.

LAH used for the chlorosilane reductions was purified from 1M LAH/ethersolution (Aldrich). The purification procedure for obtaining 40 ml ofpurified 1M LAH ether solution is as follows: 40 ml of purifiedcyclohexane was added to 40 ml commercial 1 M LAH/ether solution. Themixture was concentrated by removing the ether under vacuum, and at thesame time, white LAH precipitated out. The LAH was isolated bycentrifugation, decanting the cyclohexane, and washing with 40 mlpurified cyclohexane. The obtained white LAH was re-dissolved in 40 mlfreshly purified ether, and 40 ml purified cyclohexane was added to thesolution. The precipitation, centrifugation, and purified cyclohexanewashing steps were repeated again to get purified LAH powder. 36 mlpurified ether was added to the purified LAH to make 1M LAH/ethersolution.

To obtain high purity polysilane, the purity of the solvents and thecommercial LAH/ether solution or LAH powder is important. Afteremploying the solvent and reagent purification procedures describedabove, alkyl impurities in the polysilane were decreased to less than0.3% (from 1.4%), as determined by ¹H NMR spectroscopy (the chemicalshift [or peaks] at 0.9 ppm and 1.3 ppm are assigned to alkyl impuritygroups in the polysilane).

Example 1

Synthesis of Cp₂ZrPh₂ catalyst. Cp₂ZrCl₂ (10.18 g, 34.8 mmol) and 80 mlof DME were added to a IL Schlenk flask with a thermowell in the glovebox. An addition funnel with 25 ml of 3M PhMgBr in ether was connectedto the Schlenk flask. The setup was then connected to the Schlenk line.PhMgBr in ether was added slowly to a vigorously stirred solutionmaintained at a temperature of from 0 to 10° C. The reaction mixture wasstirred overnight at room temperature after the addition. Thereafter, 80ml of toluene was added to the reaction mixture and stirred for 30minutes in the glove box. After removing the reaction residue byfiltration, the dark green solution was dried under vacuum at 20° C. Theresulting brown product was washed three times with 40 ml ether. 7.28 gof final product was obtained after drying overnight under vacuum(yield: 56%). The Cp₂ZrPh₂ catalyst was stored in an amber vial at −30°C. ¹H NMR (d₆-benzene): δ 7.35 (d, 4H), 7.20 (t, 4H), 7.12 (q, 2H), 5.77(s, 10H). Elemental analysis, Calc: C, 70.33%; H, 5.37%; Zr, 24.30%.Anal: C, 67.83%, H, 5.29%; Zr, 23.12.

Example 2

Synthesis of polyphenylsilane. PhSiH₃ (22 g, 400 mmol) and Cp₂ZrPh₂(0.381 g, 2 mmol) were mixed together in a Schlenk flask in the glovebox. The reaction started immediately after mixing with the observationof H₂ gas evolution. The flask was then connected to Schlenk line within10 min. The reaction mixture was stirred under argon flow for 5 days atroom temperature. To remove the Zr catalyst, the yellow to brownpolyphenylsilane as synthesized was dissolved in 120 ml toluene, washed5 times with 3% HCl (150 ml acidic water, stirred for 20 min. in eachwash) and once with 150 ml DI water (stirring for 20 min). Thepolyphenylsilane solution was then purified with chromatography using 60g Florisil (Aldrich, 100-200 mesh) as the stationary phase and tolueneas solvent. About 300 ml eluant was collected into a 500 ml flask. Thetoluene was removed at room temperature and the polyphenylsilane wasfurther dried under vacuum at 80° C. for two hours to get 19.6 g clearor slightly yellow product (yield: 89%). ¹H NMR (d₆-benzene): δ 7.2 (bs,5H), 5.1 (bs, 0.2H), 4.6 (bs, 0.8H).

FIG. 5 shows a GPC trace of a typical polyphenylsilane synthesized bythis procedure. The polymer has a bimodal distribution. The lowermolecular weight fraction contains a mixture of cyclic silanes withapproximately five to six Si units. According to the number averagemolecular weight Mn as indicated in Table 1 below for the entire productdistribution, the polyphenylsilane product mixture contains an averageof about 10 to 12 Si units. Thus, the higher molecular weight fractionis believed to contain predominantly the desired linear polyphenylsilaneand have an average of more than 10-12 Si units. Thus, n, b and/or q*mmay be defined as an average number of silicon and/or germanium atoms inthe polysilane (or the dehydrocoupling reaction product mixture), ascalculated from the number average molecular weight (Mn) of thepolysilane. The cyclic compounds are reasonably unavoidable byproducts,due to the mechanism of the catalyst and the stable nature of the cycliccompounds. The average yield of cyclic compound is about 20% asdetermined by ¹H NMR spectroscopy (the proton chemical shift of cyclicsilane is around 5.1 ppm, and the linear polymer is around 4.6 ppm; see,e.g., FIG. 6A). Thus, the higher molecular weight fraction is believedto have an average of about 11 to 14 Si units.

TABLE 1 Molecular weight variation of linear polyphenylsilanes. Batch MwMn Linear %* 1 2370 1340 83 2 2280 1260 79 3 2880 1450 81 4 2094 1161 795 2310 1240 82 Mw: weight avg. molecular weight; Mn: number avg.molecular weight; *estimated from NMR spectra.

The above described polyphenylsilane purification procedureadvantageously removes substantially all of the Zr catalyst. As shown inTable 2 below, the Zr content is about 0.23% if the polyphenylsilane isonly washed with water. The amount is reduced to below 0.00001% with thecombination of water washing and chromatography. Such reductionsadvantageously improve stability of a subsequently-produced polysilane.

The stability of polysilane was tested by exposing a 15% polysilane inkin cyclooctane under light at 50° C. A higher Zr content in thepolyphenylsilane results in less stable polysilane inks. By removingsubstantially all of the Zr in the polyphenylsilane, the polysilane inkcan survive more than 20 days at 50° C. in light. An ink of polysilanessynthesized from polyphenylsilane with a higher Zr content usually formsa white precipitate within three days under the same conditions.

TABLE 2 Stability of polysilanes. Stability of Zr % in polysilane, BatchPolyphenylsilane workup polyphenylsilane days 1 Water wash only 0.23 3 2Water wash + chromatography <0.00001 >20 3 Water wash + chromatography0.00005 >20 4 Water wash + chromatography <0.00001 >20 5 Water wash +chromatography <0.00001 >20

Example 3

Synthesis of polysilane. In a 500 ml Schlenk flask, 9 g ofpolyphenylsilane obtained as above described was dissolved with 100 mlof purified cyclohexane, and 0.25 g sublimed AlCl₃ was added to thesolution. The flask was connected to a Schlenk line. The reactionmixture was frozen in liquid nitrogen and left under vacuum. Thereaction mixture was thawed with a water bath while under static vacuum.Dry HCl gas was then backfilled into the reaction flask under vigorousstirring at room temperature. The solution was stirred 3 hours undercontinuous HCl flow. After stopping the HCl flow, the solution wasstirred overnight under a static HCl atmosphere. The reaction solutionwas then connected to vacuum for about a minute to remove excess HCl.

36 ml 1M LAH solution (purified as described above) was added to theresulting polychlorosilane solution at 0 to −10° C. The addition wasfinished in about 30 min, and the reaction mixture was brought to roomtemperature and stirred overnight. Two phases were formed during thisperiod. The top clear phase containing polysilane was decanted intoanother Schlenk flask, and was concentrated to about 10 ml by vacuum.The resulting polysilane cyclohexane solution was transferred to anamber vial containing 20 ml degassed DI water. The two phases were mixedvigorously, and allowed to set for 1 min. The top phase containingpolysilane was transferred to another vial, and the same water washprocedure was repeated. After the second water wash, the polysilanephase was filtered through a 0.2 pm membrane to obtain a clear liquidwhich was dried under vacuum for 2 hours. 1.2 g of the final product wasobtained as a slightly viscous clear liquid (yield 45%). ¹H NMR(d₆-benzene): δ 3.5 (bs, SiH) (see, e.g., FIG. 6C). ²⁹Si NMR(d₆-benzene): δ-96 (SiH₃), -106 (SiH₂), -128 (SiH).

Treating the polysilane mixture with water after reduction reduces theamount of Al in the polysilane, and substantially removes Alcontamination in the Si film after spin coating. The treatment withwater may also be carried out with slightly acidic water. Exposure ofthe silane mixture to alkaline conditions should be avoided as it maylead to uncontrolled Si—Si bond scission and polymerization. Contactwith water can occur by either adding the polysilane mixture to water oradding the water to the polysilane mixture. The ratio of water topolysilane mixture is about 2:1. In most cases, washing the polysilaneonce is enough to remove most Al contamination. However, the reaction ofAl residue with water may vary due to the nature of long chain polymer.Washing the polysilane at least twice with water ensures a consistent Alremoval effect.

The polychlorosilane and polysilane are generally light and temperaturesensitive. The ¹H NMR spectrum of an isolated polychlorosilane is shownin FIG. 6B. To avoid any unwanted isomerization or generation of highermolecular weight components, the reaction setup is preferable protectedfrom light and UV, for example, using amber flask or wrapping withaluminum foil. The isolated neat polysilane is stored in amber vial atlow temperature (−30° C.).

Example 5

In separate procedures, PhSiH₃ was dehydrocoupled using Cp₂ZrPh₂ andCp₂ZrBu₂ catalysts (generated in situ by reacting Cp₂ZrCl₂ with, e.g., 2mole equivalents of PhMgBr and BuLi, respectively) to yield apolyphenylsilane. The catalyst in the resulting polyphenylsilane wasremoved as described above. Cleavage of the phenyl groups and reductionof the product as described above yielded a polyhydrosilane, which wasused in a viscous ink (e.g., about 10 wt. % in cyclooctane) forspincoating (with and without UV irradiation) and inkjet printing ofsilicon films.

Example 6

As shown in FIG. 3, cyclo-Si₅H₁O was dehydrocoupled using(Fl₂SiMe₂)ZrBu₂ catalyst (where Fl is fluorenyl), and the metal catalystwas removed by above described method to yield an oligohydrosilane,which was used in an ink (e.g., about 10 wt. % in cyclooctane) forUV-spincoating and inkjet printing of silicon films. The thus-producedoligohydrosilane exhibited beneficial effects in increasing the inkviscosity relative to similar compositions that did not include such anoligohydrosilane.

Example 7

Si Film Formation. The silane ink is formed by dissolving the polysilanein a compatible organic solvent, such as a mono- or multicyclicaliphatic hydrocarbon (e.g., cyclooctane and/or cis-decalin). The goalis to form a silane film or island from a polysilane ink by an ink-jetprinting technique. For effective inkjet printing, the ink should have aviscosity >3 cP (preferably about 10 cP) and low volatility. Inks fromthe present polysilanes meet these specifications. As shown in FIG. 7,the viscosity of the polysilane ink is above 4 cP when the mass loadingis above 15% (either wt. % or vol. %), while the viscosity of a similarcyclopentasilane ink is just around 2 cp.

A silane film was formed by a spin-coating technique. About 0.4 ml of anink containing ˜10 vol % polysilane in cyclooctane was dispensed onto asubstrate in the glove box. A silane film was formed by spin-coating theink onto the substrate with substantially simultaneous UV irradiation.The substrate with the silane film formed thereon was soft cured on ahotplate at 100° C. for about 10 min, then hard cured in a 400° C. ovenunder argon flow for 20 min. This procedure formed a hydrogenated,amorphous silicon film with a thickness of from 50 to 100 nm, dependingon the spin-coating conditions and ink concentration. A typical SIMSprofile of certain impurity atoms in the obtained film is shown in FIG.8. The carbon, oxygen, hydrogen content in the film is about 0.08%,0.03%, and 2.8%, respectively. Al is present in an amount of about 0.06ppm. Both Fe and Na content are below the SIMS detection limit.

CONCLUSION/SUMMARY

As described above, poly- and oligo-hydrosilane and -hydrogermanecompounds for semiconductor inks can be synthesized by dehydrocouplingof perhydrosilanes and perhydrogermanes (linear, branched, cyclo-,caged, poly-, or oligosilanes and/or -germanes), or by dehydrocouplingof arylhydrosilanes and arylhydrogermanes, followed by halogenativecleavage of the aryl groups and reduction to yield perhydrosilanes andperhydrogermanes. The inks can be used for production of amorphous andpolycrystalline silicon, germanium, or silicon-germanium films byspincoating or inkjet printing, followed by curing at 400-500° C. and(optionally) laser-, heat-, or metal-induced crystallization (and/ordopant activation, when dopant is present; also see, e.g., U.S.application Ser. No. 11/249,167, filed Oct. 11, 2005, and incorporatedherein by reference in its entirety). Highly doped films may be used tomake contact layers in MOS capacitors, TFTs, diodes, etc. Lightly dopedfilms may be used as semiconductor films in MOS capacitors, TFTs,diodes, etc.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the Claims appended hereto and theirequivalents.

1. A method of making a polysilane, comprising: a) combining a silane orgermane of the formula AH_(a)R¹ _(4−a), a silane, germane, orsilagermane compound of the formula A_(k)H_(g)R^(1′) _(h), acyclosilane, cyclogermane, or cyclosilagermane of the formulac-A_(m)H_(pm)R^(1′) _(rm), or a combination thereof with a catalyst ofthe formula R⁴ _(x)R⁵ _(y)MX_(z) (or an immobilized derivative thereof)to form a polyarylsilane containing at least 15 A atoms, where eachinstance of A is independently Si or Ge, a=2 or 3, each instance of R¹and R^(1′) is independently aryl, substituted aryl, or—A_(b)H_(b+1)R_(b) (where R is aryl or substituted aryl, and b is aninteger from 1 to 4), p is 1 or 2, m is from 3 to 12, and r is 0 or 1;k≧2, g≧2, and (g+h)=2k+2; M is a metal selected from the groupconsisting of Ti, Zr and Hf, x=1 or 2, y=1, 2 or 3, z=0, 1 or 2,3≦(x+y+z)≦8, each of the x instances of R⁴ is independently asubstituted or non-substituted cyclopentadienyl, indenyl, fluorenyl,siloxyl, germoxyl, hydrocarbyl, hydrocarbyloxy, hydrocarbylamino, orhydrocarbylsulfido ligand; each of the y instances of R⁵ isindependently a substituted or non-substituted hydrocarbyl,hydrocarbyloxy, hydrocarbylamino, hydrocarbylsulfido, silyl, germyl,hydride, phosphine, amine, sulfide, carbon monoxide, nitryl, orisonitryl ligand, and X is a halogen; b) reacting said polyarylsilanewith (i) a halogen source and (optionally) a Lewis acid or (ii)trifluoromethanesulfonic acid (HOTf) to form a polyhalosilane; and c)reducing said polyhalosilane with a metal hydride to form a polysilanecontaining at least 15 A atoms.
 2. The method of claim 1, comprisingreacting said polyarylsilane with said halogen source and said Lewisacid, wherein said Lewis acid comprises a compound of the formula M³_(v)X² _(w), where M³ comprises a member selected from the groupconsisting of transition metals and Group IIIA elements; v is 1 or 2; X²comprises a halogen; and w is any integer up to the number of ligandbinding sites available on the v instances of M³.
 3. The method of claim2, wherein M³ comprises Al and X² is Cl or Br.
 4. The method of claim 1,wherein said metal hydride comprises a compound of the formula M¹ _(a)M²_(b)H_(c)R⁶ _(d), where M¹ and M² are independently first and secondmetals, each R⁶ in said metal hydride compound is independently a ligandbound to at least one of M¹ and M² by a covalent, ionic or coordinationbond, at least one of a and b is at least 1, c is at least 1, and d is 0or any integer up to one less than the number of ligand binding sitesavailable on the (a+b) instances of M¹ and M².
 5. The method of claim 4,wherein said metal hydride comprises a member of the group consisting oflithium aluminum hydride, calcium aluminum hydride, sodium borohydride,aluminum hydride, gallium hydride, and aluminum borohydride.
 6. Themethod of claim 1, comprising combining said silane of the formulaAH_(a)R¹ _(4−a) with said catalyst of the formula R⁴ _(x)R⁵ _(y)MX_(z)to form the polyarylsilane.
 7. The method of claim 1, comprisingcombining said silane compound of the formula A_(k)H_(g)R^(1′) _(h) withsaid catalyst of the formula R⁴ _(x)R⁵ _(y)MX_(z) to form saidpolyarylsilane.
 8. The method of claim 1, wherein A is Si.
 9. The methodof claim 1, wherein R¹ is aryl.
 10. The method of claim 1, wherein k isan integer of from 2 to
 12. 11. The method of claim 1, wherein g is k,k+2, 2k, or 2k+2.
 12. The method of claim 11, wherein g is k+2 or 2k.13. The method of claim 1, wherein h is 0, 2, or k.
 14. The method ofclaim 13, wherein h is
 0. 15. The method of claim 1, wherein M is Zr orHf.
 16. The method of claim 15, wherein M is Zr.
 17. The method of claim1, wherein R⁴ is independently a substituted or non-substitutedcyclopentadienyl or fluorenyl ligand.
 18. The method of claim 17,wherein R⁴ is permethylcyclo-pentadienyl or fluorenyl.
 19. The method ofclaim 1, wherein R⁵ is independently a substituted or non-substitutedaryl.
 20. The method of claim 19, wherein R⁵ is phenyl or tolyl.
 21. Themethod of claim 1, wherein said catalyst has the formula R⁴ ₂R⁵ ₂M. 22.The method of claim 21, wherein R⁵ is independently a substituted ornon-substituted aryl, silyl, germyl, hydride, or phosphine ligand. 23.The method of claim 22, wherein R⁴ is independently a substituted ornon-substituted cyclopentadienyl or fluorenyl ligand.
 24. The method ofclaim 1, comprising reacting said polyarylsilane with a halogen sourceand a Lewis acid.
 25. The method of claim 1, wherein said polysilaneconsists essentially of A and hydrogen atoms.
 26. A method of making apoly(aryl)silane, comprising: a) combining a cyclosilane, cyclogermane,or cyclosilagermane of the formula c-A_(m)H_(pm)R^(1′) _(rm) with acatalyst of the formula R⁴ ₂R⁵ ₂M (or an immobilized derivative thereof)to form a polymer having at least 15 A atoms, where each instance of Ais independently Si or Ge, and each instance of R^(1′) is independentlyH, aryl, substituted aryl, or —A_(b)H_(b+1)R² _(b) (where R² is H, arylor substituted aryl, and b is an integer from 1 to 4); p is 1 or 2, m isan integer from 3 to 12, and r is 0 or 1; M is a metal selected from thegroup consisting of Ti, Zr and Hf, each of the instances of R⁴ isindependently a substituted or non-substituted cyclopentadienyl,indenyl, or fluorenyl ligand; and each of the instances of R⁵ isindependently a substituted or non-substituted aryl; b) washing saidpolymer with a washing composition comprising water; and c) contactingsaid polymer with an adsorbent sufficient to remove said metal from saidpolymer.
 27. The method of claim 26, further comprising combining asilane, germane, or silagermane compound of the formula A_(k)H_(g)R¹_(h), where k is an integer from 2 to 12, g≧2, (g+h)=2k+2, and eachinstance of R¹ is independently H, aryl, substituted aryl, or—A_(b)H_(b+1)R² _(b), with said cyclosilane, cyclogermane, orcyclosilagermane to form the polymer.
 28. The method of claim 26,wherein said washing composition comprises deionized water or diluteaqueous acid.
 29. The method of claim 26, wherein said adsorbentcomprises a chromatography gel or finely divided silicon and/or aluminumoxide that is substantially unreactive with said polymer.
 30. The methodof claim 26, comprising combining a silane, germane, or silagermanecompound of the formula AH₃R¹ _(4−a), where a is 2 or 3, with saidcyclosilane, cyclogermane, or cyclosilagermane to form the polymer.